This section is intended to introduce the reader to various aspects of art, which may be related to various aspects of the present invention that are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present invention. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art.
The use of three-dimensional (3D) graphical objects has been increasing in the last years, particularly with the emergence of metaverses. There are multiple usages for 3D objects: socializing worlds, games, mirroring worlds, simulation tools, but also 3D User interfaces, animation movies and visual effects for television. Generally, 3D virtual objects represent real money value. In socializing worlds and games, players are selling virtual objects or avatars to other players for real money. Building an experienced character within an online game is a very lengthy process that can require hundreds of hours behind the keyboard. The 3D model of a real-world object from a simulation tool allows manufacturing the real (counterfeit) object and selling it. Leaking the 3D model for a scene of the next blockbuster from Hollywood studios may result in bad press for the studios. As can be seen, in many cases, 3D objects are assets of great value for their owner.
For this reason, various strategies for encryption of 3D objects have been invented. In general, such methods take a 3D object, encrypt the 3D object by modifying some of the parameters, and output an encrypted 3D object that in many cases appears more or less random.
A first example of such encryption is described in WO 2012/000898 (also published as EP 2400476) in which a 3D object comprising a list of nodes and a list of lines or surfaces defined by the nodes. To encrypt the 3D object, the values of the nodes is shuffled. As the surfaces now are defined by other node values, the encrypted 3D object usually becomes quite random and ‘chaotic’.
A second example, described in EP 2453430, improves on the first example in that at least the node values of one dimension is shuffled independently of the node values of the other dimensions. Once again, the encrypted 3D object usually becomes quite random and ‘chaotic’.
In a third example, described in EP 11306116.2, a bit stream representing a 3D object can be encrypted and the encrypted bit stream can be interpreted as points of a further 3D object. The skilled person will appreciate that the encryption usually renders the points random and thus the further 3D object ‘chaotic’.
In a fourth example, described in EP 12168218.1, a 3D object is encrypted by generating pseudo-random vectors that are added to the original points of the 3D object. Since the vectors can be made to go in any direction, the encrypted 3D object can be quite random.
The skilled person will appreciate that the encrypted 3D objects can be rendered by a rendering device. It will also be appreciated that the geometric properties of encrypted 3D objects are different from the original 3D objects. In particular:                the basic surface (typically triangles) in an encrypted 3D object is generally significantly larger than the surface of the original object; and        the number of overlapped surfaces is significantly greater than in the original object.        
Since the rendering of 3D objects and environments makes use of rasterization, which is optimized for the usual geometry properties of 3D objects, the rendering performances of encrypted 3D objects can be highly impacted, specially the time spent in rasterization. One reason for this is that a standard renderer renders surfaces of encrypted 3D objects that, later during the rendering of the protected 3D object, are hidden by one or more further surfaces.
It will therefore be appreciated that there is a need for a system that improves the rendering of encrypted 3D objects by optimizing the time spent in rasterization without compromising the security of the encrypted 3D objects. The present invention provides at least such a system.